Yes an AU is 1 cow for 1 year thus 3 cows on 1 $2500acre would be just over $800 a cow/AU, that is unheard of anywhere in the past I don't know how many decades.  If you can get under $10K on an established place you are doing good in this day and age.

I was just down in Sulphur Springs area last month from what I remember a lot of places are claiming around 2-3acre/cow and roughly $2500/acre.  Seemed pretty attractive except for the heat at least half the year.